Heterocyclic compounds (Gr. Heteros - the other, second) - a class of organic ring compounds in cycles which, besides carbon atoms, contains more atoms of other chemical elements, so-called heteroatoms: oxygen (e.g., furan and pyran), nitrogen (pyrrole and pyridine), sulfur (thiophene tiofenaldegid, thiopyran, thiazole), selenium (selenophene) etc.
heterocycles formed by two or more carbon atoms and heteroatoms.According to the theory Bayer heterocycles are resistant only when a deviation valencies of atoms constituting the ring, will be the smallest angle of 109 ° 28 '.For example, are the most unstable heterocyclic compounds with three-term heterocycles whose molecules there is the greatest deviation of - 24 ° 44 '(ethylene oxide and ethylene tioksid ethyleneimine).
Heterocycles are widely distributed in nature.These include amino acids (tryptophan, carnosine, histidine), imino acids (proline and hydroxyproline), purine (adenine and guanine) and pyrimidine (thymine, uracil and cytosine) bases, biologically important substance of living matter (heme, hemin chlorophyll), alkaloids (caffeine and atropine), antibiotics (penicillin, gramicidin C, streptomycin), drugs (norsulfazol and caffeine), sulfonamides (norsulfazol, streptocid), organic solvents (pyridine), carbohydrates, nucleic acids, proteins, hormones, vitamins, and many otherimportant substance.
classification of chemical compounds
classification is based on the structure of the heterocycles in the molecule which carbon atoms linked to a heteroatom (hetero) atoms and hydrogen.Heterocycles and their derivatives are divided into groups depending on the number of atoms forming the cycle (three-, four-, five-, six-membered, etc.).In each group there are sub-groups with one, two or three hetero atoms.
Heterocyclic compounds in most cases referred to by the historical nomenclature (pyridine, pyrrole, acridine).From historical names formed the name of their derivatives (pyridine-4-carboxylic acid, methyl pyridine).To indicate the position of Vice-atom heterocycles number.The numbering is performed by heteroatoms, or designated by the letters of the Greek alphabet, starting from the neighboring carbon atom with a heteroatom - alpha, beta, gamma, etc.
Getorotsiklicheskie compounds: nomenclature
heterocyclic When naming compounds according to the IUPAC nomenclature counted number of atoms in the heterocycle, its structure, placement of substituents and other features (e.g., furfural has the systematic name furan-2-carbaldehyde).The names of heterocyclic compounds indicated in the description of methods for their preparation, properties and values.
K heterocycles include oxides (e.g., ethylene oxide), dibasic acid anhydrides of saturated carboxylic acids, etc.Stability heterocycles discussed earlier depends on the number of carbon atoms in the molecule heterocycle, the heteroatom itself and its location on the heterocycle.The least resistant are heterocyclic compounds, consisting of three or four cycles, which are easily broken and become acyclic compounds.There is a lot of heterocyclic compounds, molecules of stable cycles, similar cycle benzenovogo core.They are the main structural element of many biosoedineny of great importance for industry, medicine and veterinary medicine.
Chemistry of Heterocyclic Compounds
chemical properties of the five-membered (thiophene and derivatives thereof) heterocycles due to the presence of excess molecule pi electron system, which increases their aromaticity.Compared with benzene thiophene easily reacts electrophilic substitution.
